TIL: Insert directly into a table with ActiveRecord

Recently I have been on a path of trying out SQLite as an alternative to the PostgreSQL server I have running for my personal projects.

Part of this is migrating from PostgreSQL to SQLite.

After having dumped my PostgreSQL database as .json with TablePlus I then need to import it.

Luckily I found out that ActiveRecord::Base.connection have a #insert_fixture method that takes a hash and a table name.

ActiveRecord::Base.connection.insert_fixture(my_hash, "some_table_name")

Putting this together in a task looks like this:

# frozen_string_literal: true

require 'csv'

namespace :import do
  desc 'Import the database'
  task database: :environment do
    ApplicationRecord.with_connection do |conn|
      conn.disable_referential_integrity do
        Dir[Rails.root.join('storage/import/*.json')].each do |file|
          table_name = File.basename(file, '.json')

          rows = JSON.parse(File.read(file))

          puts "Importing #{rows.size} rows into #{table_name}"

          rows.each do |row|
            conn.insert_fixture(row, table_name)
          end
        end
      end
    end
  end
end